Drawing implement



- E. ,comsm DRAWING IMPLEMENT. APPLICATIQN FI I. ED JUNE 4. I520.

1,381,97 1 Patented June 21, 1 921.

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fdmzzfad Corb E. CORBIN.

DRAWING IMPLEMENT.

APPLICATION FILED JUNE 4. 1920.

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EDMUND CORBIN, OF CHICAGO, ILIIINOIS.

. DRAWING IMPLEMENT.

Application filed June 4,

the vanishing point, and to draw all lines converging to this pointwithout the use'of an extra long ruler and a long table, where thevanishing point is located beyond the limits of the drawing board.

The device consists in a novel combination and arrangement of parts tobe hereinafter described and claimed, and in order that the same may bebetter understood, reference is had to theaecompanying drawings forminga part of this-specification.

In the drawings, g V.

Figure 1 is a plan view of the implement,

Fig. 2 is an edge view of a fragment thereof; 7 a V Fig. 3 is a crosssection-on the line 33 of Fig.1; V

Fig. 4 is a plan viewshowing a modified structural detail;

Fig. 5 is a plan view illustrating the manner in which the implement isused, and

Fig. 6 is a .perspective view showing a different adjustment of theimplement.

Referring specifically to the drawings, the device resembles a T-square,with the exception that the usual rigid head is absent and in its steada resilient member to be presently described is employed. The straightedge-or blade-of the'square is shown at 10, and it is provided with inchgraduations.

To one end of the blade 10 is fastened, crosswise, a resilient strip 11projecting equal distances from the graduated or working edge of theblade, and having its outer ends fitted with forks 12 which are offsetrearwardly so that a bar 13 connected to the forks and extendingtherebetween lies spaced rearwardly from the strip 11, and parallel tosaid strip in the normal posi tion of the latter, as shown in Fig. 1.

The bar 13 is rigid, and it is pivoted'to one of the forks 12, as shownat 14, with the opposite end seating loosely between the branches of theother fork so that a cross Specification of Letters Patent.

Patented June 21, 1921. 1920. Serial No. 386,637.

pin 15 carried by the latter may seat against the outer edge of the bar,said edge being toothed or serrated, as shown at 16 to permit a lockingengagement betweenthe pin and the bar.

As the stripll is resilient it may be bowed more or less as shown inFigs. 5 and 6, this being made possible by the sliding connection of thebar 13 with the fork 12 carrying the pin 15, and the strip, in view ofits inherent expansive tendency is held bowed by said pin when it is inengagement withrthe teeth 16. "In its bowed position, the strip 11describes an arc of a circle, with the bar a1chord of such circle, andin one position of the strip bar becomes the diameter of a circle. Thestrip can be flexed to describe an. are which is more or less than thesemi-circumference of a circle, Fig. 5 showing itflexed to more than asemi-circumference, and Fig. 6 to less. The bar 13 is graduatedto'denate the radii of the various arcs the strip 11 may assume, and thestrip is set to, describe the desired, are by bowing it until the pin15seats in. a tooth 1G opposite the graduation denoting the radius 'ofthedesired are.

The strip 11 may be rigidly attached to the blade 10, but a foldableconnection as shown in Figs. 1 and 3 is preferable. Here the blade endis shown recessed to seat a tongue or shank 17 extending from the strip,with a pivot pin 18 passing there through, and a stop pin 19 seating inan edge recess 20 in the tongue.

Fig. 41 shows a separate connection between the blade 10 and the strip11. Here, the strip has a tongue 21 as before, seating in an end recessin the blade, and said tongue has a longitudinal slot 22 opening throughits inner end, and seating pins 23 passing through the recessed endportion of the blade.

The manner in which the device is used is illustrated in Figs. 5 and 6,in which the reference numeral 2 1 denotes: an ordinary drawing board.Assuming now that the'distance of the vanishing 'point'O in Fig. 5, onthe horizontal line AB from the vertical line (I-D has been ascertainedby proper calculation, the operator measures the distance from the lineC-D to the strip 11 along: the line A B,by means of the scale ontheblade '10, after which the strip is bowedto a radius corresponding tothe difference between this measurement and the distance between thelineC-D and the point 0. The operator now drives two pins 25 into the faceof the drawing boa'rd 2a in such position that they seat inside the aredescribed by the'strip 11 and in contact The blade 10 may now be used.

vanishing point is beyond the limits of the drawing board 24, as shownat O in Fig. 5. The device is set and used as hereinbefore described,and it obviates the use of a long ruler and table. The device alsorequires no extended mathematical calculation for locating the vanishingpoint, and it can be easily set to obtain the same. i V

The device can be used at either end of thedrawing board, it beingnecessary only to invert it if it is to housed at the end of the drawingboard 24 opposite the end it is shown in the drawings. The same straightedge is now used, and it will be understood that both sides of the blade10 will be graduated.

I claim:

1. A drafting implement comprising a straight-edge blade, a resilient,strip attached crosswise to one end thereof, and means for adjustingsaid strip to assume an arcuate curve, said curved strip being adaptedfor sliding contact with ameans for guiding it in a circular path havingfor its center the center of the arc to which the strip is curved.

2. A drafting implement comprising a straight-edge blade, a resilientstrip attached crosswlse'to one end thereof, means for ad j usting saidstrip to assume an areuate curve, and means associated with saidadjusting means for indicating the radius of the curvature of the strip,said curved strip being adapted for sliding contact wit-h a means forguiding it in a circular path having for its center: the center of thearc to which the strip is curved.

8. A drafting implement comprising a straight-edgeblade, a' stripattached cross- -wise to one end tl1QIQOf,"SZt1(l strip being resilientfor adjustment to assume an arcuate curve, 'anda rigid barrconnected toone; end of the strip and havingan'ad ustable connection with the otherend for effecting said adjustment 'ofthe strip, said bar having,gradiiations to indicate the radius of the curvature of the strip,said, curved strip being adapted'for sliding ;contact-with a means forguiding it in a circularpath having for its center the center of the areto which the strip is curved. f In testimony whereof I aiiix mysignature.

' ,EDMUND CORBIN;

